1. Field Of The Invention
The present invention relates to an improved surgical clip applicator for applying multiple surgical clips to body tissue or blood vessels as necessary during surgical procedures. The clip applicator stores multiple clips, avoiding reloading after application of a clip, and automatically advances the clips to the instrument jaws after placement of each successive clip. Surgical clips are applied to blood vessels, veins, arteries or tissue prior to being severed or cut as required during surgery. In this manner, the loss of blood through the severed vessel is prevented and the flow of blood into the area where the surgeon is operating is also prevented.
2. Description Of The Prior Art
Many methods of constricting blood vessels and the like have been employed over the years. These include pliers or scissors type instruments which are themselves clamped about a vessel as well as the use of small clamps applied to a vessel by a clamp applying instrument. These clamps have ranged widely in shape and size as well as in the manner in which they attach to and constrict a blood vessel.
Generally, there are two types of instruments for applying separate, individual clamping elements or clips to a blood vessel. The first type can be generally referred to as a scissors type because it consists of two arms having jaws at one end and handles at the opposite end with the arms pivotally connected near the jaw end. The instrument is activated similar to a pair of scissors; moving the handles together causes the jaws to clinch and separating the handles causes the jaws to open.
Two variations of the scissors type clip applicator exist. These are either single count clip applicators or multiple count clip applicators. As the names imply, the single clip version only holds one clip at a time and must be continually reloaded after every use. The multiple clip version either integrally contains or is adapted to receive a clip cartridge. The clip cartridge houses multiple clips which are fed to the jaws of the instrument by varying methods.
The second type of clip applicator applies camming principles rather than pivoting to clinch the jaws and deform a clip. Camming is achieved by either reciprocating the jaws within an exterior sleeve or reciprocating the sleeve about stationary jaws. In particular, the jaws can move rearward into the sleeve or the sleeve can move forward past the jaws to accomplish closing of the jaws and clinching of the clip. In either case, a camming action between the outside surface of the jaws and the forward edge of the sleeve close the jaws. This second type of clip application is manufactured in both single count or "one shot" versions or in multiple count versions. Moreover, given the present state of medical technology, these instruments are constructed primarily from plastic in order to produce a low cost instrument which justifies disposal after the single use. Of course, conventional clip appliers as well as the present invention could easily be manufactured from all metal componentry in order to be capable of sterilization and, therefore, reuse. The instrument of the present invention has reciprocating jaws within a stationary sleeve and houses multiple clips. The preferred embodiment is intended to be disposable.
The present invention improves upon the overall componentry and design of reciprocating jaw type clip applicators in general. Specifically, the present invention is constructed around a unitary, one-piece chassis which runs the length of the instrument. This insures that the components attached thereto are always properly aligned and further provides structural strength to the device not found in existing devices constructed from multiple base pieces.
A structural characteristic of reciprocating jaw type instruments which cam the jaws closed is the inability to store clips on the same plane or level as the jaw members. Typically, the jaw members are tuning fork shaped and, therefore, only a limited number of clips can be stored in the space between the jaw arms and subsequently fed to the jaws. Consequently, the clips must be housed in some type of magazine or cartridge either above or below the plane of the jaw arms in order for the instrument to house a sufficient number of clips. To resolve this problem so that clips can be fed to the jaws, the jaws themselves may be made taller or may be increased in height so that there is a deforming portion of the jaws on the same level as the clips to insure proper feed. However, with this structure the jaws of the instrument are at least twice the height necessary, and, therefore, precludes placement of the instrument in small or delicate areas.
The present invention avoids the problem of having to increase the height or size of the jaws by feeding the clips to a position between the jaw arms on the same plane as the jaws and then advancing the clips into the jaws by way of a channel or clip track formed in the jaws. As a result, the jaws are formed at a minimum height to allow placement of the instrument in close, or tight positions.
Indeed, the overall clip housing and clip advancement of the present invention is an improvement over existing designs. Many types and variations of clip housings, cartridges or magazines exist in conventional clip applicators to store and serially advance the clips. However, variations in the manufacture of the individual clips can adversely impair the operation of the instrument. For example, in a clip housing where the clips are abuttingly arranged in a single, forward facing row with the legs of each clip contacting the rearward end or crown of each preceding clip, variations in clip size or non-uniform manufacturing can cause the clips to become unaligned within the housing resulting in a misfire, jam or malfunction of the instrument.
Due to varied clip manufacturing techniques or even variations in quality control, the clip length of any clip can vary compared to any other clip. Clip length is measured from the apex of the clip to the tip of the legs. While the variance in individual clips may be minor, when the clips are arranged in a single, forward facing row, the variations can create significant differences in the overall length of the row. Consequently, because the present instrument is designed to advance the row of clips the length of one clip for each actuation of the instrument, a row of clips which is of improper length can create a jam or a misfeed.
For instance, due to even slight variation in clip length, it is conceivable that a full complement of 35 or 40 clips may be too short or too long in overall length. As a result, despite the design of an instrument to advance the row of clips one clip length for each actuation of the instrument, the forwardmost clip may not be advanced fully into the jaws of the instrument causing a misfeed or the forwardmost clip could be overfed causing the instrument to jam.
To overcome this problem, some conventional clip applicators employ clip housings where the clips are separately stored between a row of teeth and the individual clips are never in contact. In such an arrangement, varied or uneven clip manufacture is of little importance because the clips will be advanced to the next forward incremental position regardless of any discrepancies in clip length. However, the complex structure required for this type of clip advance mechanism is costly to manufacture and it reduces the number of clips which could otherwise be stored in the instrument.
The present instrument overcomes this problem by employing a clip housing or having a dual level row of clips. While the majority of clips are placed in a single, forward facing row upper level, the forwardmost three or four clips are maintained on a lower level. With each actuation of the instrument, the forwardmost clip on the lower level is advanced to the jaws and is replaced on the lower level by the forwardmost clip on the upper level. The lower level of three or four clips effectively minimizes if not negates variations in clip length.
The present invention incorporates still further improvements over conventional clip applicators with respect to its internal design. An improved clip load spring is employed for positively advancing, positioning and stabilizing the forwardmost clip as it is advanced to the jaws. Coupled with the design of the clip housing. The clips are positively controlled at every point within the instrument. As the forwardmost clip on the lower level of the clip housing is to the jaws of the instrument, the spring engages the clip at three points; the apex or crown and the tip of both legs. The clip is moved to a clip load platform which functions to align the clip with clip tracks in each jaw so that the clip can then be advanced into the jaws. This engagement insures an aligned advancement of the clip to a resilient clip load platform disposed between the jaw arms and aligned with clip tracks formed in the jaws. The design of the clip load spring also stabilizes and centerably positions the clip against the platform in order for a clip advancer or ram to engage the clip and push it into the instrument jaws and further allows it to be cammed out from between the jaws during jaw closure thereby avoiding a jamming of the instrument by the spring. As a result of the positive advance, the clip will not become misaligned nor will it jam the instrument during its movement from the lower level of the clip housing to the jaws. Moreover, and of significance, the clip spring allows the instrument to function in any position or at any angle. Because the clip is always positively controlled and advanced, the instrument can operate upside down or in any other position thereby increasing its versatility and value to surgeons.
A further improvement found in the present invention overcomes jamming problems inherent in conventional multiple clip appliers caused by prematurely actuating the instrument while a clip is being transferred to the jaws. Typically this would occur when, after deforming a clip about a vessel, the surgeon does not fully release the handles before a reactuation. In that circumstance, the complete clip feed process may not have occurred, leaving the clip positioned somewhere between the clip housing and the jaws. Consequently, premature reactuation of the instrument may cause the clip to be deformed only partially about a vessel or perhaps internal to the instrument, depending upon the location of the clip. The present instrument employs a lock-out mechanism requiring completion of the clip feed process before the instrument can be reactuated.
The instrument also employs an improved internal drive or transmission mechanism for advancing the clips to the jaws. Particularly, the transmission mechanism includes a gear drive for sequentially actuating the clip feed and clip deformation componentry. The gear drive includes a spur or segment gear having a modified lead tooth profile that allows the transmission mechanism to operate more efficiently and with less force applied by the surgeon.
Not only is the operation and the internal mechanisms of a clip applicator critical but the overall size and exterior shape must allow the device to fit a wide range of hands and also be lightweight and easily maneuvered. Oftentimes a surgeon desires to forego the intended grasp of an instrument and "choke-up" or move his hand closer to the jaw end in order to obtain greater leverage or a more comfortable grasp of the instrument. Operating the instrument in this manner distributes the operating forces throughout the surgeon's entire hand rather than concentrating the forces in his thumb and first one or two fingers. Consequently, palming the instrument in this manner prevents fatigue and tiring of the surgeon's hand allowing him to more effectively undertake longer surgical procedures.
Most present clip applicators and ligators are not suitable for palming. These instruments are susceptible to pinching the operators hands and, because of the internal operating mechanisms, the instruments require a radial closure of the handles which effectively precludes palming the instrument. The present invention is ergonomically designed to fully close with less than ten degrees movement of the handles and, as a result of the design, is operable in the palm of almost any size hand.